The present invention relates to a cardboard container or box for packaging and unwinding coiled welding wire.
In recent times, a substantial industry has been developed around providing coils of electric welding wire in square cardboard boxes. This new technology is described in Gelmetti U.S. Pat. No. 5,494,160 and Cipriani EPC Application No. 1,057,751 A1. This patent and published application are incorporated by reference herein to illustrate the use of cardboard boxes with center cores to package and allow unwinding of coiled welding wire. It is common also to provide a center octagonal liner, as shown in the EPC application to define spaced triangular corner cavities each filled with a tubular reinforcing element. Such tubular elements are shown in Obetz U.S. Pat. No. 1,640,368 and Stump U.S. Pat. No. 3,648,920. These patents disclosing corner reinforcing elements for cardboard boxes are incorporated by reference as background information regarding the use of corner tubular support members or elements. Tubular support members are also shown in brochures entitled xe2x80x9cThe Squaring of the Circlexe2x80x9d and xe2x80x9cWeld Point Robotic Welding Wirexe2x80x94Technology of the Futurexe2x80x9d. These printed publications are incorporated by reference herein to illustrate reinforced corners in square boxes, some of which include an octagonal inner lining against which the welding wire is pushed during the coiling operation. All of these prior patents and publications are incorporated by reference as background to the present invention.
The prior art discussed above illustrates the development of square cardboard boxes for packaging and unwinding of welding wire, wherein the cardboard boxes are modified by a variety of structural elements to solve the many and diverse problems experienced by use of cardboard boxes. Using the background technology relating to cardboard boxes for welding wire, it has been determined that the best results are accomplished using a square box having an octagonal center lining and an inner core around which the wire is coiled. This basic box construction allows the wire to be coiled around the center core so it fills the space between the center core and the inner lining. By using the inner lining, the wire actually engages eight different surfaces to restrict its outer dimension and confine its radial spread during coiling, shipping, and unwinding. The unique combination of a square cardboard box and an octagonal center lining around an inner core produces four triangular cavities at the corners of the cardboard box. In accordance with standard technology, these four triangular cavities are filled by vertical reinforcing elements in the form of tubes or triangles generally matching the cavities. Such reinforcing elements increase vertical ridigity of the box, thus allowing shipment of several stacked boxes. Selection of a cardboard box with a center lining and reinforcing corner elements satisfies several diverse needs and solves problems associated with the recent trend toward the use of cardboard boxes for welding wire. Advantageous features from several box structures are thus obtained in a single container. However, the prior box technology with or without a liner required restriction of the coiled wire. Otherwise, there was deformation of the square cardboard box forming the package. As shown in Gelmetti U.S. Pat. No. 5,494,160, the coil is maintained in the center of the box by spaced diagonal wood strips. The Gelmetti box does not include a center octagonal liner. Consequently, when using the advantageous combination of a square box and a center octagonal liner, the coil tended to expand against the side walls of the box, causing the box to assume a non-square, generally circular configuration, especially after long shipping and storage times. For this reason, the advantageous combination of the octagonal liner in a square box with corner reinforcing has been used primarily with a structure to control the outward movement of the coil such as ties, as shown in the prior publication entitled xe2x80x9cThe Squaring of the Circlexe2x80x9d.
The present invention overcomes difficulties experienced in prior attempts to employ the superior concept of a square cardboard box with an octagonal inner liner and corner reinforcing elements. In the past, the coil around the center core would engage the four side walls of the box to bow the box outwardly and effect the appearance and use of the cardboard box. Solving this problem by tying the wire coil merely reduced the amount of wire that could be loaded into the box. The invention involves an improvement in the basic design, which improvement overcomes the tendency of the box to bow out without reducing the capacity of the box constraining the wire coil.
In accordance with the invention, the well known corner reinforcing elements are modified to create an integral pressure rib extending from the apex of a corner toward the diagonal wall of the center liner. This rib, in the preferred embodiment, is wide enough to force the diagonal wall to bow outwardly. When wire is coiled about the core and engages the four diagonal side walls of the inner liner, the pressure rib extending from the apex of the corners is engaged and creates a line of force from the wire coil directly to the vertical apex at all four corners of the cardboard box. In this manner, the corners are placed in tension to counteract the tendency of the side walls to bow outwardly when the liner is engaged by the wire coiled around the center core. By merely forming the corner support elements to include an integral, diagonally extending pressure rib, the box maintains its square configuration even during shipping and long storage. Consequently, the hat or adapter used at the welding operation to affix a wire conduit above the center of the box easily fits over the box. In the past, the hat had to reshape the cardboard box into a square. In some instances, this presented difficulty. By merely modifying the center reinforcing tubes to provide a pressure rib between the liner and the apex of each corner, a loaded box is placed in tension and the square shape is maintained. This change in the corner structure of the container allows the advantages known to exist by using a square container with an octagonal center liner. The coil does not need to be restrained, and the box does not experience undue distortion. There is no need to sacrifice the advantage of a center liner so the wire coil can be maintained in a center position as in the Gelmetti patent. The capacity of the container is maximized, while still rigidifying its shape.
In accordance with the present invention, there is provided a container for packaging and unwinding a welding wire. The container comprises a square cardboard box with four vertical walls and four vertically extending corners, each defining an apex. There is a center cylindrical core and an inner, vertically extending tubular liner with an octagonal shape defined by four outer walls, each generally overlying the side wall of the box, and four alternate inner walls between two of the outer walls and spaced from the corner apexes to define generally triangular vertical cavities. The box has an at rest dimension from the apex of the corner to the inner walls of the liner. The container is provided with standard vertically extending corner reinforcing element in each of the triangular corner cavities. In accordance with the invention, the reinforcing element of each cavity has a diagonally extending pressure rib extending from the apex of the corner to the inner wall of the liner. The width of this pressure rib is greater than the at rest dimension of the corner cavity. Consequently, the rib pushes the wall inwardly. A coil of welding wire around the core presses on the inner wall to apply a force along the apex of the box corner. This places the corners of the box in tension to counteract the tendency of the wire to bow the sides of the box into the shape of the coiled wire. In accordance with an aspect of the invention, the pressure rib is formed integrally with the vertical reinforcing element. Preferably, the element is formed from folded cardboard. After the container is used, all parts of the box can be recycled as used cardboard. In accordance with a broader aspect of the invention, the rib does not bow the liner wall inwardly, but is used to prevent outward bowing of the liner wall. Any tendency to bow outwardly engages the pressure rib, forcing the rib against the corner to rigidify the box and maintain its squareness.
The primary object of the present invention is the provision of a container for packaging and unwinding welding wire, which container utilizes the concept of a square cardboard box with a center octagonal liner while overcoming the tendency for the box to deform during shipment, storage, and use.
A further object of the present invention is the provision of a container, as defined above, which container is only a minor modification of existing containers and involves a low expense while obtaining the desired results of maintaining box squareness.
Still a further object of the present invention is the provision of a square cardboard box having a center octagonal cardboard liner with a modified corner reinforcing element that has a pressure rib extending from the apex of four box corners to the liner in the box so that filling of the box does not change its square configuration.
These and other objects and advantages will become apparent from the following description taken together with the accompanying drawings.